Take starter out of fridge and feed it. If it has water just pour that out.
Feed the starter about 20 grams of water and 20 grams of flour, mix it, and then return back to fridge before you go to bed or let it sit out until it gets to be room temperature. It should double in size and start to get some good bubbles.
Note: When feeding your starter, always use a 1:1 ratio of water to flour.
Start by mixing:
Mix thoroughly and wait 10 minutes to let it activate without the starter.
Add the following ingredients:
Fold the dough to incorporate the ingredients.
Place in the warmest part of your house, covered, for an hour.
Remember to feed the starter and put it back in the fridge.
Fold the dough again a few times.
Cover and let it sit for 30 minutes.
Fold again, cover with a towel, and let it sit overnight.
Clean and flour your surface. Dump the dough onto the counter, then stretch it out and fold it up.
Place the folded part up (upside down) in the proofing basket covered lightly with a paper towel for an hour.
Flip the dough over into a baking dish using parchment paper. Make a small cut along the top to open up the bread.
Lay out the parchment paper and put some flour in the middle, then plop the dough onto the flour. Tuck in the sides a bit - if it's sticky, add a bit more flour. Then cut a little slit down the middle.
Bake at 470°F (preheated):
When preheating the oven, you can stick the pan in the oven so that it preheats too!